1. Field of the Invention
The present invention relates to an image forming apparatus, more particularly, to an image forming apparatus which is adapted to prevent a photosensitive drum from being irradiated with external light when a cover of the image forming apparatus is opened.
2. Description of the Related Art
In image forming apparatuses, a laser scanning unit illuminates a photosensitive drum to form an image thereon. When a sheet of recording medium passes between the photosensitive drum and the transfer roller, the image formed on the photosensitive drum is transferred onto the sheet of recording medium. However a problem occurs when the cover of the image forming apparatus has to be opened. Light from the outside illuminates the photosensitive drum causing the image formed on the photosensitive drum from the laser scanning unit to be ruined.
What is needed is a protective covering for the photosensitive drum that prevents light from the outside to illuminate the photosensitive drum when the cover is opened. This will prevent spoiling the image on the photosensitive drum when the cover to the image forming apparatus is opened.
It is therefore an object to provide an image forming apparatus that provides a protective plate that covers the photosensitive drum and prevents light from outside the image forming apparatus from illuminating the photosensitive drum when the cover to the photosensitive drum is opened.
It is also an object of the present invention to provide a method that prevents light from outside the image forming apparatus from destroying an image formed on a photosensitive drum by a laser scanning unit when the cover of the image forming apparatus is opened.
It is further an object to provide a protective cover that automatically covers the photosensitive drum When the cover of the image forming apparatus is opened.
It is still also an object of the present invention to provide an image forming apparatus in which an exposed portion of the photosensitive drum, through which light from the laser scanning unit is irradiated, is protected from external light when the developing device is separated from the main body of the image forming apparatus.
To achieve the above objects and other advantages, there is provided an image forming apparatus having a main body, a cover for opening/closing a portion of the main body, a laser scanning unit for irradiating a laser light on a photosensitive drum disposed at a developing device, a exposing hole which is formed at a side of the developing device to exposing a surface of the photosensitive drum to the light from the laser scanning unit and a protecting plate for covering the exposing hole to protect the exposing hole from external light when the cover is opened. Preferably, the developing device is provided with a supporting portion which is engaged with the protecting plate, and the cover is formed with an operational protrusion to rotate the protecting plate and thus expose the exposing hole. Preferably, the protecting plate is formed with a supporting protrusion which is engaged with the supporting portion, and the supporting protrusion has a returning spring for returning the protecting plate when an external force exerted by the operational protrusion is eliminated.